Saturday, March 05, 2011

Brian Wang Presents Carnival of Nuclear Energy #42

1. Idaho samizdat - Progress noted in Texas and Virginia. The nuclear renaissance in the U.S. had some tough going in 2010. The low point of the year was Constellation's decision to walk away from the Calvert Cliffs III reactor project over a dispute with the federal government about loan guarantees. The project may be turning around and there is more good news to report in Texas and Virginia. That said anti-nuclear groups are as active as ever engaging the U.S. Nuclear Regulatory Commission (NRC) in a seemingly endless stream of contentions over licensing issues.
2. Nuclear Green comments on Doing Due diligence on future energy options

A recent essay by Robert Rapier on the Oil Drum titled "Doing Due Diligence" calls attention to an issue that Nuclear Green has repeatedly addressed, the failure to perform due diligence regarding future energy options. One example, involves two businesses, EEStor of Austin, Texas and ZENN Motors of Canada. A second example, involves the failure of energy researcher Mark Z. Jacobson to preform his due diligence obligations. Finally claims made by Greenpeace concerning the cost of Concentrated Solar Power in 2050 were subjected to due diligence tests, and found to be flawed.

A new technology for extracting power from a nuclear reactor's heat production may bring both higher efficiencies and more compact sizing to small modular reactors. Supercritical CO2 brayton cycle turbines are smaller and more efficient than steam turbines with similar power ratings.

...the supercritical CO2 Brayton cycle provides the same efficiency as helium Brayton systems but at a considerably lower temperature (250-300 C). The S-CO2 equipment is also more compact than that of the helium cycle, which in turn is more compact than the conventional steam cycle.

Under normal conditions materials behave in a predictable, classical, “ideal” way as conditions cause them to change phase, as when water turns to steam. But this model tends not to work at lower temperatures or higher pressures than those that exist at these critical points. In the case of carbon dioxide, it becomes an unusually dense “supercritical” liquid at the point where it is held between the gas phase and liquid phase. The supercritical properties of carbon dioxide at temperatures above 500 C and pressures above 7.6 megapascals enable the system to operate with very high thermal efficiency, exceeding even those of a large coal-generated power plant and nearly twice as efficient as that of a gasoline engine (about 25 percent). In other words, as compared with other gas turbines the S-CO2 Brayton system could increase the electrical power produced per unit of fuel by 40 percent or more. The combination of low temperatures, high efficiency and high power density allows for the development of very compact, transportable systems that are more affordable because only standard engineering materials (stainless steel) are required, less material is needed, and the small size allows for advanced-modular manufacturing processes. _ScienceBlog